The present invention relates to a method and an apparatus for monitoring the tensile force on a thread. It relates more particularly to an electronic system for analyzing an electrical signal which is indicative of said tensile force.
The invention may advantageously be employed with a known thread tension measuring device. One such device is disclosed in Federal Republic of Germany DE-OS No. 3,506,698, which corresponds to commonly-assigned U.S. application Ser. No. 833,201, filed Feb. 25, 1986, allowed, the disclosures of which are incorporated herein by reference. This device measures thread tensile force by generating an output signal indicative of the tensile force, which is contemplated to be transmitted to a central computer system.
In U.S. Ser. No. 833,201, one end of a spring element is clamped fast to a frame. The spring element is provided at its free outer end with a low-friction diabolo, which may be dumbbell-shaped, and over which a thread is guided. Also on the free end is a permanent magnet. Mounted at a fixed position on the frame at a given distance from the magnet is a Hall effect sensor. The diabolo bears against the thread, which is guided through the frame, so that the spring element is flexed to a greater or lesser degree in response to the tension on the thread. The Hall effect sensor detects the resulting movements of the magnet, whereby an electrical signal is generated which is indicative of the thread tension.
A computer system is contemplated to evaluate the data from one or more work stations, and sound an alarm or stop the thread, for example, if the thread tension is too low or too high. The computer system may also have a display.
Disadvantageously, however, operating personnel at the work stations do not receive any information in this prior art system.